Field
The present disclosure relates to a chimney structure including internal partitions having a common center, a reactor including the chimney structure, and/or a method of manufacturing the chimney structure.
Description of Related Art
In a reactor, for example an Economic Simplified Boiling Water Reactor (ESBWR), a chimney structure may be arranged between the reactor core outlet and the steam separator inlet to establish, enhance, and deliver natural circulation of a fluid (e.g., a steam and water mixture) in the reactor vessel. A chimney structure may have internal partitions to ensure the steam water mixture flows in the vertical direction and/or to establish better natural circulation flow inside the reactor.
Many ESBWR reactors include a square-cell chimney structure having a round tube that surrounds a grid pattern of internal partitions. The internal partitions may define square cells and regions of small cross-section inside the round tube. For example, the square-cell chimney structure may be a round tube with square pegs as internal partitions inside the round tube.
In a square-cell chimney structure, portions of the internal partitions near the periphery (i.e., adjacent to the round tube surrounding the internal partitions) can define regions of small cross-section. Portions of the internal partitions that are not adjacent to the periphery can define the square cells. The steam water mixture flowing through the regions of small cross-section may have a higher pressure drop across the chimney structure than the steam water mixture flowing through the square cells. Consequently, during the operation of the reactor, the steam-water mixture flowing through the regions of small cross-section may be susceptible to undesirable flow regime changes.
Manufacturing the square-cell chimney structure may include numerous bending and welding steps to shape the internal partitions into a grid pattern and to join the internal partitions to the round tube. If the internal partitions have manufacturing defects, the numerous bends in the internal partitions may cause stress concentrations in the internal partitions. As a result, during the operation of a reactor including a square-cell chimney structure, the numerous welds and bends in the square-cell chimney structure have to be inspected frequently as part of periodic maintenance. The regions of small cross-section in the square-cell chimney structure may be more difficult to make and inspect during the operation of the reactor.
Additionally, placing the square-cell chimney structure in a reactor may include forming complex connections between the internal partitions of the square-cell chimney structure and a bottom or a top support piece. During a refueling operation, it may be necessary to remove the internal partitions of the square-cell chimney structure. Disconnecting the connections between the internal partitions of the square-cell chimney structure and a bottom or a top support piece may extend the reactor downtime during a refueling operation.
Accordingly, a chimney structure that reduces the regions of small cross-section defined by internal partitions, reduces the number of welds and bending steps in manufacturing the chimney structure, reduces the number of welds that are inspected during periodic maintenance, and/or has less pressure drop if a fluid (e.g., steam water mixture) flows through the chimney structure may be desired.